/*
类的继承
*/
(function () {
    class Animal {
        run(distance = 0) {
            console.log(`Animal run ${distance}m`);
        }
    }
    class Dog extends Animal {
        cry() {
            console.log('wang! wang!');
        }
    }
    const dog = new Dog();
    dog.cry();
    dog.run(12);
})();
